1. Field of the Invention
The present invention relates to a message data processing method for a mobile communications terminal, to a mobile communications terminal, and a message data processing program for a mobile communications terminal. More specifically, the present invention relates to a technology for enhancing security by preventing others from viewing the contents of message data.
2. Description of Related Art
Mobile telephones can be carried around with ease, and allow not only phone calls, but also the exchange of message data as in e-mail, and hence have become very popular in recent years. However, since they can be carried around and used easily, thereby leading to possibly having information read therefrom by others.
As such, in order to prevent the contents of received message data from being read by others, mobile telephones are equipped with such functions where user operation is rejected and each function is locked and its use prohibited. In the present specification, this will be referred to as dial lock function. The dial lock function is activated when a user operates the mobile telephone in a specific manner, or by repeatedly receiving a call from a designated number.
This dial lock function can only be activated when the user intends for it to be activated. However, since e-mails in mobile telephones are distributed in a push-fashion from a server, information is added to mobile telephones at times unexpected by the user. Therefore, if a mobile telephone is left on a desk without having the dial lock function activated, some other person may read the newly received e-mail. In other words, because e-mails often arrive at unexpected times, it is difficult for the user to activate the dial lock function effectively.
In addition, in Japanese Patent Application Publication 2001-339509 (pages 6 and 7, and FIGS. 1 through 3), there is disclosed a mobile communications terminal apparatus having a key lock function for rejecting key operations. In this mobile communications terminal apparatus, when a text message is received in a state where the key lock function is activated, the key lock function is automatically deactivated, and then, if no key operations are subsequently performed, or if the apparatus is left in standby mode for a predetermined period of time, the lock is reactivated.
However, in this mobile communications terminal apparatus disclosed in Japanese Patent Application Publication 2001-339509, because the key lock is deactivated when a text message is received, it is possible for other people to read the contents of the message. In addition, although this mobile communications terminal apparatus is designed so that the lock is reactivated if no key operations are performed, or if the apparatus is left in standby mode for a predetermined period of time, other people may still be able to read the contents of the message before the lock is reactivated. Thus, mobile telephones in the past have not necessarily been able to ensure adequate security.